U.S. patent number 6,926,862 [Application Number 09/871,764] was granted by the patent office on 2005-08-09 for container, shelf and drawer liners providing absorbency and odor control.
This patent grant is currently assigned to Kimberly-Clark Worldwide, Inc.. Invention is credited to Jeanette Ann Allen, Monica Carlise Fontenot, Terry Pearce Ford, John Wesley Fowler, Ryan Clinton Frank, Gina Kay Rolsten, Richard John Schmidt, Bruce Scott Williamson.
United States Patent |
6,926,862 |
Fontenot , et al. |
August 9, 2005 |
Container, shelf and drawer liners providing absorbency and odor
control
Abstract
A container liner, shelf liner or drawer liner that will absorb
liquids spilled or leaked into a container or onto a shelf or
drawer. The liner is a layered product having a layer which is
impervious to liquids and an absorbent layer. The absorbent layer
further contains a material which is capable of controlling odors,
such as those odors found in refrigerators and waste receptacles.
The liner of the present invention provides the benefit of
absorbing spills and controlling odors in containers such as
refrigerators and waste receptacles.
Inventors: |
Fontenot; Monica Carlise
(Williamsville, NY), Ford; Terry Pearce (Woodstock, GA),
Fowler; John Wesley (Alpharetta, GA), Allen; Jeanette
Ann (Alpharetta, GA), Frank; Ryan Clinton (Atlanta,
GA), Rolsten; Gina Kay (Lawrenceville, GA), Schmidt;
Richard John (Roswell, GA), Williamson; Bruce Scott
(Alpharetta, GA) |
Assignee: |
Kimberly-Clark Worldwide, Inc.
(Neenah, WI)
|
Family
ID: |
25358068 |
Appl.
No.: |
09/871,764 |
Filed: |
June 1, 2001 |
Current U.S.
Class: |
422/5; 422/120;
422/122; 428/370; 428/68; 428/74; 428/76; 514/58 |
Current CPC
Class: |
A61F
13/551 (20130101); A61L 9/00 (20130101); A61L
9/014 (20130101); A61L 15/46 (20130101); B65F
1/0006 (20130101); B65F 7/00 (20130101); A61L
2300/404 (20130101); A61L 2300/408 (20130101); Y10T
428/2924 (20150115); Y10T 428/23 (20150115); Y10T
428/239 (20150115); Y10T 428/237 (20150115) |
Current International
Class: |
A61F
13/15 (20060101); A61L 15/16 (20060101); A61L
15/46 (20060101); A61L 9/00 (20060101); A61L
9/01 (20060101); A61L 9/014 (20060101); B65F
1/00 (20060101); B65F 7/00 (20060101); A61L
009/00 () |
Field of
Search: |
;422/5,120,122
;424/76.21,443 ;514/58 ;428/68,74,76,370,374 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO |
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01/30658 |
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May 2001 |
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WO |
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Other References
International Search Report dated Aug. 29, 2002 for International
Application No. PCT/US02/08519..
|
Primary Examiner: Jastrzab; Krisanne
Attorney, Agent or Firm: Ambrose; Robert A.
Claims
What is claimed is:
1. A liner adapted for use with a container, drawer or shelf to
absorb spills of liquids and/or odor control within said container,
drawer or on said shelf, said liner comprising a liquid impervious
backing layer; and an odor controlling liquid absorbent layer
comprising a stabilized matrix of thermoplastic fibers, an
absorbent material and an odor controlling material; wherein said
liquid absorbent layer is a coform material comprising about 5% to
about 70% by weight of the thermoplastic fibers, between about 94%
to about 19% by weight of absorbent material and about 0.5% to
about 60% by weight of odor controlling material.
2. The liner according to claim 1, further comprising a liquid
pervious layer wherein the odor controlling liquid absorbent layer
is positioned between the liquid pervious layer and the liquid
impervious layer.
3. The liner according to claim 2, wherein the liquid pervious
layer comprises a spunbond layer of polyolefin fibers, said
polyolefin fibers further comprising a wetting agent.
4. The liner according to claim 1, wherein the absorbent material
comprises wood pulp.
5. The liner according to claim 1, wherein the odor controlling
material is selected from the group consisting of baking soda
(sodium bicarbonate), activated charcoal, activated carbon, clays,
diatomaceous earths, and zeolites.
6. The liner according to claim 5, wherein the odor controlling
material comprises baking soda.
7. The liner according to claim 1, wherein the odor controlling
liquid absorbent layer comprises a plurality of layers, each layer
of the absorbent layer comprising thermoplastic fibers and an
absorbent material, wherein at least one of the absorbent layers
further comprises the odor controlling material.
8. The liner according to claim 7, wherein the odor controlling
liquid absorbent layer comprises two layers, a first layer and a
second layer, wherein the first layer is adjacent to the liquid
impervious layer, said first layer comprises thermoplastic fibers,
an absorbent material and the odor controlling; and the second
layer is adjacent to the first layer and is distal to said liquid
impervious layer.
9. The liner according to claim 8, further comprising a liquid
pervious layer wherein the first and second absorbent layers are
positioned between the liquid pervious layer and the liquid
impervious layer.
10. The liner according to claim 9, wherein the liquid pervious
layer comprises spunbond polypropylene, the thermoplastic fibers of
the absorbent layers comprise polypropylene, the absorbent material
comprises wood pulp, the odor controlling material comprises baking
soda and the liquid impervious layer is a polyethylene film.
11. The liner of claim 1, wherein the odor controlling material is
present in an amount of about 1% to about 40% by weight of the
coform material.
12. The liner according to claim 8, wherein the first layer is a
coform material comprising thermoplastic fibers in the range of
about 30-65% by weight and the absorbent material in the range of
about 65-30% by weight end about 1-40% by weight of the odor
controlling material; and the second layer is a coform material
comprising thermoplastic fibers in an amount of about 10-40% by
weight and the absorbent material in the range of about 90-60% by
weight.
13. The liner according to claim 12, wherein the odor controlling
material comprises about 5-20% by weight of the total weight of the
first and second layers, taking into account the total weight of
the odor controlling material, the thermoplastic polymers, and the
absorbent material present in both the first and second layer.
14. The liner according to claim 13, further comprising a liquid
pervious layer positioned adjacent to said second layer, distal to
said first layer.
15. The liner according to claim 14, wherein the liquid pervious
layer comprises spunbond polypropylene, the thermoplastic fibers of
the absorbent layers comprises polypropylene, the absorbent
material comprises wood pulp, the odor controlling material
comprises baking soda and the liquid impervious layer comprises a
polyethylene film.
16. The liner of claim 1, wherein the odor controlling liquid
absorbent layer further comprises an ethylene scavenger, an oxygen
scavenger, a carbon dioxide scavenger, a fungicide or an
antibacterial agent.
17. The liner of claim 2, wherein the liquid pervious layer has a
point unbonded bond pattern.
18. The liner of claim 17, wherein the liquid pervious layer is
prepared from multicomponent fibers.
19. A container comprising the liner of claim 1.
20. A refrigerator comprising the liner of claim 1.
21. A trash receptacle comprising the liner of claim 1.
22. A shelf comprising the liner of claim 1, wherein the liner is
positioned on an upper surface of the shelf.
23. A drawer comprising the liner of claim 1, wherein the liner is
positioned inside the drawer.
24. A method of controlling odor and/or spills of a liquid in a
container, drawer or on a shelf, said method comprising placing
odor controlling liquid absorbent liner in said container, drawer
or on a shelf, an odor controlling liquid absorbent liner
comprising liquid impervious backing layer; and an odor controlling
liquid absorbent layer comprising a mixture of thermoplastic
fibers, an absorbent material and an odor controlling material;
wherein said liquid absorbent layer is a coform material comprising
about 5% to about 70% by weight of thermoplastic fibers, between
about 94% to about 19% by weight of absorbent material and about
0.5% to about 60% by weight of odor controlling material and
further wherein said liquid absorbent odor controlling layer is
positioned between said liquid pervious outer layer and said liquid
impervious backing layer.
25. The method of claim 24, wherein said container is a
refrigerator and said liner is placed on an upper surface of a
shelf or in a drawer of said refrigerator.
26. The method of claim 24, wherein said container is a waste
receptacle.
Description
FIELD OF THE INVENTION
The present invention generally relates to an absorbent liner that
provides odor control. More particularly, the present invention
relates to absorbent liners that are used in locations where both
odor control and liquid absorbency are needed, such as in
refrigerators and cabinets, and around or in containers, such as,
trash receptacles.
BACKGROUND OF THE INVENTION
Food and beverage spills in and around a kitchen will often present
the problems of clean-up and odor control. This is especially true
in refrigerators and waste receptacles in kitchens. Many times, a
spill or a leak from a food or beverage container in a refrigerator
goes unnoticed until the user of the refrigerator desires the item
which has been spilled or which has leaked. By the time the item is
desired, the spill or leak usually has solidified or has begun to
solidify, leaving a hard to remove stain or residue on the
refrigerator shelf or drawer. Often, this stain or residue will
emit malodorous aromas into the refrigerator. The same is true for
food stored in cabinets. Therefore, there is a need in the art to
provide an effective means for absorbing such spills in
refrigerators and cabinets and providing odor control.
Trash receptacles also present problems with liquid clean up. In
the case of trash receptacles, a food or beverage containing
bottle, can, jar, or resealable package, containing residual food
or beverage is often thrown into a trash receptacle. This residual
food or beverage content will often leak into the trash container.
Most trash receptacles do not have an effective means for
controlling leaks or spills of liquid food items. While plastic
bags are often used to line a trash receptacle, many times these
bags are damaged during installation, use or removal. In the case
of a damaged plastic bag, any liquids in the plastic bag may leak
into the trash receptacle. These liquids will often solidify or
began to solidify leaving a residue, which may emit malodorous
aromas. As will be recognized, the same issues are faced with
disposal of nonconsumable trash, such as, for example, pet litter.
Therefore, there is a need in the art to provide an effective
liquid absorbing and odor control means in trash receptacles.
In addition, various foods stored in a refrigerator or cabinets
often emit strong aromas. For example, aromas from garlic, cheeses,
meats and/or spices will often permeate a refrigerator when these
food items or dishes containing these food items are stored in a
refrigerator, even for a short period of time. Many times, the
aroma from one food item will blend with the aroma or flavor of
another food item or overpower the aroma or flavor of another food
item stored in the refrigerator. Likewise, spices and other food
items, such as coffee, will often permeate a cabinet in which these
items are stored. This often results in the wasting of food, due to
the lost of flavor or appeal of a food item which has been
overpowered by the aroma or flavor of another food item.
Many techniques have been employed to reduce this problem over the
years. The most frequent technique is to carefully wrap food items,
for example with plastic films, prior to storage in the
refrigerator or cabinet. However, some odors or aromas from the
wrapped food may still escape, due to various reasons, such as,
incomplete wrapping, odors too strong to be effectively contained,
or damage to the wrapping due to movement of food items in and out
of the refrigerator and/or cabinet.
Other techniques used to reduce this problem include placing an
open box of baking soda or other odor controlling substance in the
refrigerator or cabinet. However, this technique presents the
problem of spills of the contents of the open box into the
refrigerator or cabinet, which may result in the contamination of
food items stored in refrigerators or cabinets. Further, this
technique of odor control is not effective in controlling spills or
leaks in the refrigerator.
There are several other prior art odor adsorbing devices. For
example, U.S. Pat. No. 5,046,604 to Forhetz et al. teaches an odor
adsorbing liner that has pouches of odor adsorbing particles
between two sheets. The pouches are prepared by stitching the
sheets together in a quilt-type fashion. The sheets of material are
disclosed as paper or cloth. The product of the '604 patent suffers
from the problem that the odor absorbing particles are loose in the
pouches and if one of the sheets becomes torn, the particles can be
released into the refrigerator or cabinet. Further, the liners are
difficult to cut to a specific size for a particular shelf or
drawer since the areas containing the loose particles cannot be
cut. If these sheets were cut in the pouch area, the loose
particles in the pouch would no longer be contained within the
pouch area, thereby causing the particles to be removed from the
liner, which in turn will reduce the effectiveness of the odor
adsorbing liner of the '604 patent.
In a similar manner, JP11-230665 teaches enveloping porous charcoal
and carbon fibers with a nonwoven fabric. As with U.S. '604,
enveloping of the active components presents the problem of the
active particle becoming loose within the refrigerator.
Other prior art methods include placing a pouch of odor adsorbing
particles into a device which hangs in a refrigerator shelf. Such
devices are described in U.S. Pat. No. 5,772,959 to Bermas and U.S.
Pat. No. 5,468,477 to Bermas. The odor adsorbing particles of these
patents are sealed within a porous paper or a nonwoven polymeric
felt. The device of these patents is effective in controlling odor
within a refrigerator and/or cabinet, however, the device does not
provide any means of controlling or managing spills which may occur
within a refrigerator or cabinet.
In addition to the above-described methods, JP58-79518 discloses a
refrigerator freshening device having an odor adsorbing material.
The odor adsorbing material is a liquid absorber supported on a
porous material. This odor adsorbing material is placed in a gas
permeable film, wherein the film is impermeable to liquids. It is
necessary for the film to be liquid impermeable since the liquid
adsorber of the odor adsorbing material may leak from the device.
As is clearly taught by JP '518, nonwoven materials are not
suitable to contain the odor adsorber.
Attempts have been made in the art to control odors in containers,
such as soiled diaper storage containers. U.S. Pat. No. 5,022,553
to Pontius discloses a nonwoven liner for a diaper container,
wherein the nonwoven liner is impregnated with an odor adsorbing
material. This patent, however, does not suggest that the nonwoven
material is also capable of absorbing liquids.
Fibrous liquid absorbent pads are known in the art and have widely
been used in personal care products, such as diapers, catamenial
devices (tampons and sanitary napkins), incontinence pads and the
like, to absorb bodily fluids. In recent years, various attempts
have been made to impart odor control to these absorbent pads. See,
for example, U.S. Pat. No. 4,826,497 to Marcus et al., U.S. Pat.
No. 5,122,407 to Yeo et al., EP 0 515 473 to Procter & Gamble
Company, EP 0 509 409 to Kimberly Clark Corporation and EP 0 389
015 to Procter & Gamble Company. Included in the methods
suggested by these patents is the incorporation of odor adsorbing
material in the formed articles. However, none of these patents
suggest that a liner for a container, shelf or drawer can be made
from these materials.
Further, fibrous absorbent pads have been used in a variety of
other uses, such as bed pads (U.S. Pat. No. 4,650,481 to O'Conner),
pet pads (U.S. Pat. No. 4,961,930 to Perdelwitz, Jr. et al), infant
car seat pads( U.S. Pat. No. 4,886,697 to Perdelwitz, Jr. et al.)
and floor covers or floor mats (U.S. Pat. No. 4,609,580 to Rockett
et al.). Again, none of these patents suggest using the fibrous
absorbent pads as a liner for a container, shelf or drawer.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a
container liner, shelf liner or drawer liner that can absorb
liquids spilled or leaked into a container or onto a shelf or
drawer.
Further, it is another object of the present invention to provide a
container liner, shelf liner or drawer liner that can provide and
maintain a fresh environment, without the disadvantage of the prior
art shelf and drawer liners.
In addition, it is an object of the present invention to provide a
container liner, a shelf liner or a drawer liner that can absorb
spills of liquids while providing an odor neutralizing or
controlling effect.
It is another object of the present invention to provide a
disposable container liner, shelf liner or drawer liner that is
cost efficient and can be easily disposed of upon absorbing a
liquid or after the odor adsorbing material is no longer effective.
The absorbent container liner, shelf liner or drawer liner of the
present invention can simplify the clean up of such spills due to
the absorbent and disposable nature of the liner of the present
invention.
Another aspect of the present invention is to provide a method of
controlling odors in a container. This aspect of the invention is
achieved by placing the liner of the present invention into a
container, such as a refrigerator, cabinet or trash receptacle.
An additional aspect of the present invention is to effectively
increase the effective surface area of the odor controlling
material as compared to other prior art odor controlling methods
mentioned above.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-section for the liner of the present
invention.
FIG. 2 is a cross-section for a liner of the present invention.
FIG. 3 is cross-section of a preferred embodiment of the present
invention.
FIG. 4 is a perspective view of a preferred embodiment of the
present invention.
FIG. 5 is a top elevational view of the pattern-unbonded nonwoven
fabric which can be used as a liquid pervious layer.
FIG. 6 is a cross-sectional side view of the pattern-unbonded
fabric of FIG. 5 along section line 1--1 .
DETAILED DESCRIPTION OF THE INVENTION
The liner of the present invention comprises
a liquid impervious backing layer; and
an odor controlling liquid absorbent layer comprising a stabilized
matrix of thermoplastic fibers, an absorbent material and an odor
controlling material.
As used herein, the term "stabilized matrix" means that the
components of the matrix are essentially entrapped within the
matrix, and only a very minor amount of the components of the
matrix, if any, are capable of falling out of the matrix during
handling and/or use.
The liner of the present invention is adapted for use as a liner
for a container, a drawer or a shelf. As used herein, the term
"container" means an object which is capable of holding other
items. Examples of containers include, but are not limited to,
refrigerators, cabinets, waste receptacles and boxes, etc. Given
the liquid absorbing properties of the liners, the liners of the
present invention are especially suited for containers which spills
or leaks of liquids may occur. The liner of the present invention
is especially adapted for use in a refrigerator drawer or bin
and/or on a refrigerator shelf. As used herein, the term
"refrigerator drawer" is intended to include, but not limited to,
vegetable bins, meat storage bins and other such compartments
commonly found in refrigerators. The liner of the present invention
is also especially adapted to control odors the use environment, in
addition to absorbing liquids.
As used herein, the term "polymer" generally includes, but is not
limited to, homopolymers, copolymers, such as for example, block,
graft, random and alternating copolymers, terpolymers, etc. and
blends and/or modifications thereof. Furthermore, unless otherwise
specifically limited, the term "polymer" shall include all possible
spacial configurations of the molecule. These configurations
include, but are not limited to, isotactic, syndiotactic and/or
random symmetries.
As used herein, the phrase "odor controlling liquid absorbent
layer" means a structure which has the ability to both absorb
liquids and control, neutralize and/or adsorb odors.
Illustrated in FIG. 1, the liner 10 of the present invention
generally comprises at least two components, an odor controlling
liquid absorbent layer 14 and a liquid impervious backing layer
16.
The odor controlling liquid absorbent layer 14, which may comprise
one layer or a plurality of layers, is capable of absorbing
liquids, such as, but not limited to, milk, sodas and other food
related liquids. The odor controlling liquid absorbent layer 14
comprises a mixture of materials comprising thermoplastic fibers,
an absorbent material and an odor controlling material.
The odor controlling liquid absorbent layer can comprise coform
materials, although other suitable absorbent fabrics comprising a
combination of thermoplastic fibers, an absorbent material and an
odor controlling material may likewise be used in accord with the
present invention. As used herein, the term "coform material" means
composite materials comprising a mixture or stabilized matrix of
thermoplastic fibers and a second non-thermoplastic material. As an
example, coform materials may be made by a process in which at
least one meltblown die head is arranged near a chute through which
the non-thermoplastic material are added to the web while it is
forming. The second non-thermoplastic material may be, for example,
pulp, superabsorbent particles, cellulose fibers, staple fibers and
other particles. In the present invention, the non-thermoplastic
material is the combination of the absorbent material and the odor
controlling material. Exemplary coform materials are disclosed in
commonly assigned U.S. Pat. No. 5,284,703 to Everhart et al.; U.S.
Pat. No. 5,350,624 to Georger et al.; and U.S. Pat. No. 4,100,324
to Anderson et al.; the entire content of each is incorporated
herein by reference.
The thermoplastic fibers of the odor controlling liquid absorbent
layer can be prepared from any thermoplastic polymer. Generally,
the thermoplastic fibers are prepared from polyolefins, polyesters
of polyamides. The most preferred polymer materials for the
thermoplastic fibers of the absorbent layer are polyolefins, such
as polyethylene and polyproplyene from the standpoint of cost and
properties of the polyolefins. Typically, the thermoplastic fibers
have a diameter up to about 15 microns, however, it is preferred
that the diameter is between about 0.5 microns and about 10
microns.
Suitable absorbent materials include, but are not limited to,
fibrous organic materials such as woody or non-woody pulp such as
cotton, rayon, recycled paper, pulp fluff and also include
inorganic absorbent materials such as superabsorbent materials
and/or treated polymeric fibers. The absorbent materials may be
used alone or in combination with other absorbent materials.
As used herein a "superabsorbent" or "superabsorbent material"
refers to a water-swellable, water-soluble organic or inorganic
material capable, under favorable conditions, of absorbing at least
about 10 times its weight and, more desirably, at least about 20
times its weight in an aqueous solution containing 0.9 weight
percent sodium chloride. Organic materials suitable for use as a
superabsorbent material in conjunction with the present invention
include, but are not limited to, natural materials such as guar
gum, agar, pectin and the like; as well as synthetic materials,
such as synthetic hydrogel polymers. Such hydrogel polymers
include, for example, alkali metal salts of polyacrylic acids,
polyacrylamides, polyvinyl alcohol, ethylene, maleic anhydride
copolymers, polyvinyl ethers, methyl cellulose, carboxymethyl
cellulose, hydroxypropylcellulose, polyvinylmorpholinone, and
polymers and copolymers of vinyl sulfonic acid, polyacrylates,
polyacrylamides, polyvinylpyrridine, and the like. Other suitable
polymers include hydrolyzed acrylonitrile grafted starch, acrylic
acid grafted starch, and isobutylene maleic anhydride polymers and
mixtures thereof. The hydrogel polymers are preferably lightly
crosslinked to render the materials substantially water insoluble.
Crosslinking may, for example, be accomplished by irradiation or by
covalent, ionic, van der Waals, or hydrogen bonding. The
superabsorbent materials may be in any form suitable for use in
absorbent composites including particles, fibers, flakes, spheres
and the like. Typically the superabsorbent material, when present,
is present within the absorbent layer in an amount from about 5 to
about 95 weight percent based on total weight of the absorbent
body. Superabsorbents are generally available in particle sizes
ranging from about 20 to about 1000 microns. Examples of suitable
commercially available superabsorbents are SANWET IM 3900 available
from Hoescht Celanese located in Portsmouth, Va. and DRYTECH 2035LD
available from Dow Chemical Co. located in Midland, Mich.
The odor controlling liquid absorbent layer desirably has
sufficient absorbent material to absorb at least about 1 gram of
liquid per gram or and preferably about 3 grams to about 12 grams
of liquid per gram of the liner, without the use of a
superabsorbent. If a larger liquid capacity is desired or needed,
the addition of the superabsorbent material will increase the
absorbency of the liner.
In one embodiment, the odor controlling liquid absorbent layer 14
can comprise a coform material having a basis weight of at least
about 35 gsm (grams per square meter), and more desirably comprises
a coform material having a basis weight from about 70 gsm to about
340 gsm coform material. A coform material having a basis weight of
about 70 gsm to about 180 gsm is most preferred.
Suitable odor controlling material of the odor controlling liquid
absorbent layer can be any material known to those skilled in the
art which will effectively control, neutralize and/or adsorb odor.
Preferably, the odor controlling material is a solid material.
Examples of such materials include, but are not limited to, baking
soda (sodium bicarbonate), activated charcoal, activated carbon,
clays, diatomaceous earths, and zeolites. These odor controlling
materials can be used alone or in combination with one another.
Typically, the loading of the odor controlling material is between
about 2 gsm and about 80 gsm, depending of the basis weight of the
absorbent layer. More preferably, the loading of the odor
controlling material is between about 8 gsm and about 40 gsm; most
preferably between about 12 gsm and 30 gsm. As with the absorbent
material, the odor controlling material can be incorporated into
the liquid absorbent layer using the coform process by adding an
additional chute for the odor controlling material. On a percentage
basis, the odor controlling material is generally present in an
amount of about 0.5 to about 60% by weight of the odor controlling
liquid absorbent layer. If the amount of the odor controlling
material is below about 0.5% by weight, effective odor control may
not be achieved. If the amount of the odor controlling material is
more than about 60% by weight, additional odor controlling effects
may not be observed. Further, if the amount of the odor controlling
material present in the odor controlling liquid absorbent layer is
above 60% by weight, the additional odor controlling material may
be removed from the liner during handling, which creates the
additional problem of clean-up of the dust resulting from the
removal of the additional odor controlling agent from the liner.
Preferably, the odor controlling material is between about 1 and
about 40% by weight of the odor controlling liquid absorbent layer,
and more preferably between about 5 and about 20% by weight.
The odor controlling liquid absorbent layer may also be prepared
from other nonwoven fabrics or nonwoven webs. As used herein the
term "nonwoven fabric" or "nonwoven web" means a web having a
structure of individual fibers or threads which are interlaid, but
not in an identifiable manner as in a knitted or meshed fabric.
Nonwoven fabrics or webs have been formed from many processes such
as for example, meltblowing processes, spunbonding processes,
air-laid and bonded-carded web processes.
The odor controlling material could also be incorporated into the
absorbent layer by other methods known to those skilled in the art.
For example, the odor controlling material may be prepared in situ
in the absorbent layer. As an example, the absorbent layer could be
impregnated with liquid soda ash via various methods known to those
skilled in the art. The soda ash could then be converted to sodium
bicarbonate by immersing the treated absorbent layer in humid
carbon dioxide. Other similar methods could be used to incorporated
the odor controlling material in the absorbent layer.
In the meltblowing process, fibers are generally formed by
extruding a molten thermoplastic material through a plurality of
fine, usually circular, die capillaries as molten threads or
filaments into converging high velocity, usually hot, gas (e.g.
air) streams which attenuate the filaments of molten thermoplastic
material to reduce their diameter, which may be to microfiber
diameter. As used herein, the term "microfibers" means small
diameter fibers having an average diameter not greater than about
10 microns. In a preferred embodiment the microfibers may have an
average diameter of from about 0.5 microns to about 10 microns.
Thereafter, the meltblown fibers are generally carried by the high
velocity gas stream and are deposited on a collecting surface to
form a web of randomly dispersed meltblown fibers. Such a process
is disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin et
al. and U.S. Pat. No. 5,213,881 to Timmons et al.; the entire
content of each is incorporated herein by reference. Meltblown
fibers are often microfibers which can be continuous or
discontinuous and are generally tacky when deposited onto a
collecting surface.
In the spunbonding process, fibers are formed by extruding molten
thermoplastic material as filaments from a plurality of fine,
usually circular capillaries of a spinneret with the diameter of
the extruded filaments then being rapidly reduced as by, for
example, in U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat.
No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to
Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney,
U.S. Pat. No. 3,502,763 to Hartman; U.S. Pat. No. 3,542,615 to Dobo
et al.; and U.S. Pat. No. 5,382,400 to Pike et al.; the entire
content of each is incorporated herein by reference Spunbond fibers
are generally not tacky when they are deposited onto a collecting
surface and thus often require additional mechanical or chemical
bonding to form an integrated stabilized web.
As a further example, the absorbent material may be held in a web
of thermoplastic staple fibers such as, for example, air-laid or
bonded-carded webs. The liquid absorbent layer may comprise one or
more layers and additional absorbent materials may be dispersed
within the one or more layers to increase the absorbency as
desired. Typically, the odor controlling material is adhered to the
thermoplastic polymer of the odor controlling layer or are
intertwined with thermoplastic polymer and the absorbent material,
which results in the stabilized matrix of the present invention. As
an example U.S. Pat. No. 4,784,892 to Storey et al. teaches an
absorbent material of meltblown fibers with an absorbent fibrous
material (e.g. wood pulp) as well as superabsorbent dispersed
therein; the contents of the aforesaid patent is incorporated
herein by reference. Other processes known to those skilled in the
art can be used including the processes disclosed U.S. Pat. No.
4,469,734 to Minto et al., U.S. Pat. No. 5,720,832 to Minto et al.
U.S. Pat. No. 4,797,318 to Brooker et al. and U.S. Pat. No.
4,429,001 to Koplin et al.; the contents of each is incorporated by
reference in its entirety. In addition, the absorbent layer may
comprise an absorbent layer of thermoplastic fibers and absorbent
material wherein the weight percent of thermoplastic fibers to
absorbent fibers to odor absorbing material varies through the
depth of the fabric.
When the odor controlling material is held in place by the
thermoplastic polymer or other method described in the above
described U.S. patents, typically the odor controlling material is
dispersed throughout the odor controlling liquid absorbent layer
and the odor controlling material is prevented from dropping out of
the layer. It is important to note that the efficacy of the odor
controlling material is not and should not be adversely affected by
the method in which the odor controlling material is held in the
odor controlling liquid absorbent layer. It is this holding in
place of the odor controlling material which allow the liner of the
present invention to be cut to a desired shape without the loss of
the odor controlling material from the portion of the liner to be
used.
In the present invention, the preferred odor controlling liquid
absorbent layer is a coform material. The coform material should
preferably contain, taking into account only the absorbent material
and thermoplastic fibers, between about 5% to about 70% by weight
of thermoplastic fibers and about 95% to about 30% by weight of the
absorbent material. More preferably, the coform material should
contain, taking into account only the absorbent material and
thermoplastic fibers, between about 10% to about 60% by weight of
thermoplastic fibers and about 90% to about 40% by weight of the
absorbent material.
The odor controlling liquid absorbent layer should comprise, taking
into account the odor controlling material, thermoplastic fibers
and absorbent material, about 1 to about 60% by weight odor
controlling material, about 5% to about 70% by weight of
thermoplastic fibers and about 94% to about 19% by weight of the
absorbent material. More preferably, the coform material should
contain, between about 1 to about 40% by weight of odor controlling
material, about 10% to about 60% by weight of thermoplastic fibers
and about 89% to about 25% by weight of the absorbent material.
Most preferably, the odor controlling material should be about 5 to
about 20% of the odor controlling absorbent layer. In one preferred
embodiment, the odor controlling material is baking soda, the
thermoplastic fiber comprises a polyolefin fiber, and the absorbent
material comprises wood pulp. The preferred polyolefin is
polypropylene.
The liquid impervious layer 16 may be any suitable material that is
impervious to liquids. As used herein, the term "liquid impervious"
means that a film, laminate or other fabric is relatively
impermeable to the transmission of liquids, having a hydrohead of
at least about 10 cm. Hydrohead as used herein refers to a measure
of the liquid barrier properties of a fabric. The hydrohead test
determines the height of water (in centimeters) which the fabric
will support before a predetermined amount of liquid passes
through. A fabric with a higher hydrohead reading indicates it has
a greater barrier to liquid penetration than a fabric with a lower
hydrohead. The hydrohead test can be performed according to Federal
Test Method Standard 191A, Method 5514 or using a hydrostatic head
tester available from Marlo Enterprises, Inc. of Concord, N.C.
Unlike Method 5514, when using a hydrostatic head tester, the
specimen is subjected to a standardized water pressure, increased
at a constant rate until the first sign of leakage appears on the
surface of the fabric in three separate areas. (Leakage at the
edge, adjacent clamps is ignored.) Unsupported fabrics, such as a
thin film, can be supported to prevent premature rupture of the
specimen.
Typically, the impervious backing layer is prepared from a
polymeric film. Examples of polymers which can be used to form the
impervious film include, polymers and copolymers of olefins, nylon
and polyesters. The actual polymer used to prepare the film is not
critical to the invention. Given the disposable nature of the liner
of the present invention, however, it is desirable to use polymer
films having a low cost. Therefore, films of polyethylene or
polypropylene are desired due to the low cost and reasonable
strength provided by these polymers at an effective film thickness.
Typically, the impervious layer has a thickness less than about 2
mils. The impervious layer preferably has a thickness between about
0.5 and about 1.5 mils.
In addition, the liquid impervious layer may be a multilayer
nonwoven laminate which is relatively impervious to the
transmission of liquids. As used herein "multilayer nonwoven
laminate" means a laminate comprising a plurality of layers wherein
at least one of the layers is a nonwoven fabric. As an example,
laminates wherein some of the layers are spunbond and some
meltblown such as a spunbond/meltblown/spunbond (SMS) laminate and
others as disclosed in U.S. Pat. No. 4,041,203 to Brock et al.;
U.S. Pat. No. 5,169,706 to Collier et al.; U.S. Pat. No. 5,145,727
to Potts et al.; U.S. Pat. No. 5,178,931 to Perkins et al.; and
U.S. Pat. No. 5,188,885 to Timmons et al.; the entire contents of
which are incorporated herein by reference. Such a laminate may be
made by sequentially depositing onto a moving forming belt first a
spunbond fabric layer, then a meltblown fabric layer and last
another spunbond layer and then bonding the laminate in a manner
described below. Alternatively, the fabric layers may be made
individually, collected in rolls, and combined in a separate
bonding step. Multilayer laminates may also have various numbers of
meltblown layers or multiple spunbond layers in many different
configurations and may include other materials such as films (F),
e.g. SMMS, SM, SF, SFS, etc.
The multilayered nonwoven laminate should have a hydrohead of at
least about 10 cm or more and, even more desirably, has a hydrohead
in excess of about 20 cm. In one embodiment, the multilayer
nonwoven laminate can comprise a laminate of a first layer
comprising at least a 6 gsm layer of thermoplastic polymer
microfibers and a second layer comprising at least an 8 gsm layer
of spunbond fibers; more desirably the multilayer laminate
comprises from about 10 gsm to 25 gsm meltblown fibers and 15 gsm
to about 34 gsm spunbond fibers. As used herein, the term
"microfibers" means small diameter fibers having an average
diameter not greater than about 10 microns. In a preferred
embodiment the microfibers may have an average diameter of from
about 0.5 microns to about 10 microns. Microfibers can include both
meltblown fibers and/or fine spunbond fibers. With such a two layer
laminate, the microfibers would preferably face the absorbent layer
and the spunbond fibers should face the opposed outer or distal
side of the liner. The liquid impervious layer may also include
additional layers and desirably the total basis weight of the
barrier laminate is less than about 102 gsm and even more desirably
between about 20 gsm and about 68 gsm. In a further embodiment, the
multilayer laminate can comprise a spunbond/meltblown/spunbond
(SMS) laminate. Lower basis weight laminates, with good barrier
properties such as disclosed in commonly assigned U.S. Pat. No.
5,492,751 to Butt et al., the entire content of which is
incorporated herein by reference, are believed suitable for use in
the present invention.
Preferably, the liquid impervious layer is a polyethylene film
having a thickness in the range of about 0.5 mils to about 1.5
mils.
In order to help reduce slippage of the liner during use, an outer
surface of the liquid impervious layer that will come into contact
with the container, drawer or shelf desirable has a coarse, rough
or tacky surface.
In addition to the liquid impervious layer and the odor controlling
liquid absorbent layer, the liner may additionally contain a liquid
pervious layer and which allows movement of the liquid away from
its source to the absorbent layer. As used herein, the phrase
"liquid pervious" is defined as a material that is permeable to
liquids. When the liquid pervious layer is present, this structure
of which is shown in FIG. 2, the layered structure is such that the
odor controlling liquid absorbent material 14 is positioned between
the liquid pervious layer 12 and the liquid impervious layer
16.
In order to retain the desired level of liquid permeability, the
liquid pervious layer should have high void spacing and a basis
weight less than about 70 gsm, preferably between about 5 gsm and
65 gsm, and most preferably between 10 gsm and 50 gsm . Desirably,
the liquid pervious layer comprises a nonwoven web, such as, for
example, continuous spunbond fiber webs, bonded/carded webs, staple
fiber webs and/or hydroentangled webs. Suitable materials for the
fibers of the liquid pervious layer include thermoplastic polymers
such as polyolefins, polyamides (nylons), polyesters and copolymers
and blends thereof.
The liquid pervious layer 12 may comprise either hydrophilic or
hydrophobic material. Additionally, the liquid pervious layer can
comprise both hydrophilic and hydrophobic components which
desirably give the layer an overall hydrophilic character. As an
example, the liquid pervious layer can comprise a nonwoven web
comprising a mixture of hydrophilic and hydrophilic fibers. The
liquid pervious layer preferably promotes transfer of liquid away
from the outer surface of the liner to the absorbent layer.
Preferably, the liquid pervious layer does not retain fluid.
Many thermoplastic polymers, including polyolefins, are inherently
hydrophobic. Thus, in those instances where it is desired that the
liquid pervious layer be hydrophilic, the fibers may require
treatment to impart wettability or hydrophilic properties to the
fibers. Methods of treating polymers to make them hydrophilic are
disclosed in U.S. Pat. No. 4,920,168 to Nohr et al.; U.S. Pat. No.
3,973,068 to Weber; and U.S. Pat. No. 5,759,926 to Pike et al.;
each is hereby incorporated by reference in its entirety. In
addition, known surfactants, also known as wetting agents, can be
used to impart wettability to the fibers, such as, for example, non
ionic surfactant composed of a blend of sorbtan monooliate and
ethoxylated hydrogenated castor oil which is commercially available
under the tradename Ahcovel Base N62 from ICI America, Inc.
Polyolefin fiber webs desirably comprise from about 2% to about 10%
surfactant which is added to the polymer prior to extrusion. Once
formed, the surfactant migrates to the surface of the fiber
imparting wettability to the fiber.
In the present invention, it is preferred that a liquid pervious
layer is present on the liner. It is further preferred that the
liner is a spunbond layer. It is further preferred the polymer used
to prepare the spunbond layer is a polyolefin, in particular, a
polypropylene. It is further desirable that the polyolefin contains
a wetting agent. As is stated above, this spunbond layer should
have a basis weight of less than about 70 gsm and more preferably
between about 10 gsm and about 50 gsm.
A preferred aspect of the present invention is shown in FIG. 3. In
FIG. 3, the liner 10 of the present invention is shown as a
four-layer structure. A liquid pervious layer 22 is placed over two
liquid absorbent layers 24 and 25. One or both of the liquid
absorbent layers can contain the odor controlling material.
However, if only one layer of the absorbent material contains the
odor controlling material, it is preferred that the layer 25, which
is adjacent to the liquid impervious layer 26, contains the odor
controlling material. It is advantageous to have the odor
controlling material in the absorbent layer distal to the top of
the liner, since the odor controlling material may be soluble in
the liquid absorbed by the liquid absorbent layer. With an
additional absorbent layer above the layer containing the odor
controlling material, containment of the fluid in which comes into
contact with this layer may prevent from the liquid from coming
into contact with the odor controlling material. This may allow the
liner to still control odors even if the absorbent layer has come
into contact with a liquid. Further, having the two layer structure
gives the liner better fluid management.
Each of the absorbent layers can be made from different materials.
In a preferred embodiment of the present invention, the absorbent
layers are both are coform materials. It is further preferred that
the layer 25 adjacent to the liquid impervious layer, hereinafter
called the first layer 25, contains the odor controlling material
and the layer 24 which is distal to the impervious layer, herein
after called the second layer 24, does not contain the odor
controlling material. In addition, it is preferred that the first
layer 25 is a coform material which contains a thermoplastic fiber
in the range of about 30-65% by weight, the absorbent material in
the range of about 65-30% by weight, and about 1-40% by weight of
the odor controlling material. The second layer 24 is preferably a
coform material and contains about 10-40% by weight of
thermoplastic fibers, and about 90-60% by weight of the absorbent
material. In both of these layers, it is preferred that the
thermoplastic polymer is a polyolefin and the absorbent material is
wood pulp. It is further preferred that the odor controlling
material is present in an amount of about 5 to about 20% by weight,
based on the weight of the odor controlling material, the
thermoplastic polymers, and the absorbent material in both layers
24 and 25. It is also preferred that the odor controlling material
is baking soda.
In order to impart the densified areas to channel any spilled fluid
away from the point of liner impact, the nonwoven web of fibers can
be bonded such as, for example, comprising autogenously bonded webs
or point bonded webs. Bonding can be accomplished by through-air
bonding (TAB), thermal point bonding, ultrasonic bonding or other
known bonding techniques. In order to improve the handling of the
liner, point bonded fabrics desirably employ a repeating pattern of
relatively small bond points. Employing such a pattern is believed
to create a fabric texture more pleasing to the touch, i.e. with
improved hand feel.
As used herein, the term "autogenous bonding" refers to bonding
between discrete parts and/or surfaces independently of external
additives such as adhesives, solders, mechanical fasteners and the
like. As an example, multicomponent fibers may be autogenously
bonded by through-air bonding whereby inter-fiber bonds develop at
fiber contact points.
As used herein "point bonded" means bonding one or more fabrics
with a pattern of discrete bond points. As an example, thermal
point bonding often involves passing a fabric or web of fibers to
be bonded between a pair of heated bonding rolls. One of the
bonding rolls is usually, though not always, patterned in some way
so that the entire fabric is not bonded across its entire surface,
and the second or anvil roll is usually a smooth surface. As a
result, various patterns for calender rolls have been developed for
functional as well as aesthetic reasons. One example of a pattern
has points and is the Hansen Pennings or "H&P" pattern with
about a 30% bond area with about 200 bonds/square inch as taught in
U.S. Pat. No. 3,855,046 to Hansen and Pennings. The H&P pattern
has square point or pin bonding areas wherein each pin has a side
dimension of 0.038 inches (0.965 mm), a spacing of 0.070 inches
(1.778 mm) between pins, and a depth of bonding of 0.023 inches
(0.584 mm). The resulting pattern has a bonded area of about 29.5%.
Another typical point bonding pattern is the expanded Hansen
Pennings or "EHP" bond pattern which produces a 15% bond area with
a square pin having a side dimension of 0.037 inches (0.94 mm), a
pin spacing of 0.097 inches (2.464 mm) and a depth of 0.039 inches
(0.991 mm). Another typical point bonding pattern designated "714"
has square pin bonding areas wherein each pin has a side dimension
of 0.023 inches, a spacing of 0.062 inches (1.575 mm) between pins,
and a depth of bonding of 0.033 inches (0.838 mm). The resulting
pattern has a bonded area of about 15%. Yet another common pattern
is the C-Star pattern which has a bond area of about 16.9%. The
C-Star pattern has a cross-directional bar or "corduroy" design
interrupted by shooting stars. Other common patterns include a
diamond pattern with repeating and slightly offset diamonds with
about a 16% bond area and a wire weave pattern, having generally
alternating perpendicular segments, with about a 19% bond area.
Typically, the percent bonding area varies from around 10% to
around 30% of the area of the fabric laminate web. Point bonding
may be used to hold the layers of a laminate together and/or to
impart integrity to individual layers by bonding filaments and/or
fibers within the web.
In another aspect of the present invention, the liquid pervious
layer may be bonded in a pattern unbonded pattern. As used herein
"pattern unbonded" or interchangeably "point unbonded" or "PUB",
means a fabric pattern having continuous bonded areas defining a
plurality of discrete unbonded areas. The fibers or filaments
within the discrete unbonded areas are dimensionally stabilized by
the continuous bonded areas that encircle or surround each unbonded
area, such that no support or backing layer of film or adhesive is
required. The unbonded areas are specifically designed to afford
spaces between fibers or filaments within the unbonded areas. An
Example of a pub pattern is shown in FIG. 5.
Referring to FIGS. 5 and 6, an embodiment of the pattern-unbonded
nonwoven material 54 of the liquid pervious layer of the present
invention is illustrated. The nonwoven fabric or web having
continuous bonded areas 56 that define a plurality of discrete,
dimensionally-stabilized unbonded areas 58. Within the continuous
bonded areas 56, the fibers or filaments of the nonwoven web are
thoroughly bonded or fused together, and desirably are non-fibrous,
whereas within the unbonded areas 58, the fibers or filaments of
the nonwoven fabric or web are substantially or completely free of
bonding or fusing and retain their fibrous structure. It is pointed
out that other shapes for the unbonded area other than circles can
be used.
A suitable process for forming the pattern-unbonded nonwoven
material of this invention includes providing a nonwoven fabric or
web, providing opposedly positioned first and second calender rolls
and defining a nip there between, with at least one of said rolls
being heated and having a bonding pattern on its outermost surface
comprising a continuous pattern of land areas defining a plurality
of discrete openings, apertures or holes, and passing the nonwoven
fabric or web within the nip formed by said rolls. Each of the
openings in said roll or rolls defined by the continuous land areas
forms a discrete unbonded area in at least one surface of the
nonwoven fabric or web in which the fibers or filaments of the web
are substantially or completely unbonded. Stated alternatively, the
continuous pattern of land areas in said roll or rolls forms a
continuous pattern of bonded areas that define a plurality of
discrete unbonded areas on at least one surface of said nonwoven
fabric or web. The PUB pattern is further described in U.S. Pat.
No. 5,858,515 to Stokes et al, the contents of which are hereby
incorporated by reference.
The fibers or filaments used in making pattern unbonded nonwoven
liquid pervious layer may have any suitable morphology and may
include hollow or solid, straight or crimped, single component,
conjugate or multicomponent fibers or filaments, and blends or
mixes of such fibers and/or filaments, as are well known in the
art. As used herein the term "multicomponent fibers" or "conjugate
fibers" refers to fibers which have been formed from at least two
polymers extruded from separate extruders but spun together to form
one fiber. Bicomponent fibers refer to a common, specific class of
multicomponent fiber wherein the fiber comprises two distinct
components. The polymers are arranged in substantially constantly
positioned distinct zones across the cross-section of the fibers
and extend continuously along the length of the fibers. The
configuration of such a fibers may be, for example, a sheath/core
arrangement wherein one polymer is surrounded by another or may be
a side-by-side arrangement, a pie arrangement or an
"islands-in-the-sea" arrangement. Conjugate fibers are taught in
U.S. Pat. No. 5,108,820 to Kaneko et al.; U.S. Pat. No. 4,795,668
to Krueger et al.; and U.S. Pat. No. 5,336,552 to Strack et al.
Multicomponent fibers are also taught in U.S. Pat. No. 5,382,400 to
Pike et al. and may be used to produce crimp in the fibers by
drawing the multicomponent fibers with heated air; the entire
contents of the aforesaid patent is incorporated herein by
reference. For bicomponent fibers, the polymers may be present in
ratios of 75/25, 50/50, 25/75 or any other desired ratios. The
fibers may also have shapes such as those described in U.S. Pat.
No. 5,277,976 to Hogle et al.; U.S. Pat. No. 5,466,410 to Hills;
and U.S. Pat. Nos. 5,069,970 and 5,057,368 to Largman et al., which
describe fibers with unconventional shapes.
Generally, it is preferred that the fibers used to prepare the PUB
pattern are lofty in nature. However, it is important to note that
the fibers are selected such that the liquid pervious layer
promotes the transfer of the liquid away from the outer surface of
the liner to the absorbent layer.
As a preferred embodiment when the liquid pervious layer is a
material which has a patterned unbonded pattern, the fibers used to
prepare liquid pervious nonwoven web are multicomponent
thermoplastic fibers. Desirably the liquid pervious layer comprises
a nonwoven web of bicomponent fibers such as, for example, fibers
comprising a polyethylene polymer component and a polypropylene
polymer component. One or more components of the multicomponent
fibers of the liquid pervious nonwoven web can be hydrophilic.
All such nonwoven webs may be pre-bonded, using known nonwoven web
bonding techniques such as the hot air knife, compaction rolls,
through air bonding, ultrasonic bonding and stitchbonding, and
subsequently bonded using the pattern-unbonded method, or
alternatively, such nonwoven webs may only be bonded using the
pattern-unbonded method.
In preparing the liner of the present invention, any method known
to those skilled in the art can be used. For example, each nonwoven
layer of the liner may be prepared by sequentially depositing
nonwoven layer onto a moving belt. The process of U.S. patent
application Ser. No. 09/419,039, filed Oct. 15, 1999 in the name of
Riddell and which is commonly assigned to the assignee of the
present invention, can be used to prepare the liner of the present
invention. The entire contents of this patent application is hereby
incorporated by reference. Alternatively, each nonwoven layer may
be individually prepared, collected in rolls and combined in a
subsequent bonding step. It is noted that when the liquid
impervious layer is a film, it may be necessary to adhesively
attach the film to the nonwoven layers. It is further noted that
the method used to prepare the liner is not critical to the
invention.
The multiple layers of the liner can be bonded together along the
edge 42 of the liner 10. The multiple layers may be bonded such as,
for example, by thermal bonding, ultrasonic bonding, mechanical
crimping, stitching and/or adhesively bonded. Bonding the edges of
the liner may prevent the liquid absorbed in the odor controlling
liquid absorbent layer remain in this layer during use or remove of
the liner in the use environment. In addition, bonding the edges of
the liner may prevent any odor controlling material and/or
absorbent material which may fall out of the stabilized matrix
during shipping or handling of the liners from coming into contact
with the use environment or the users of the liner. It is noted
that it is not absolutely necessary for the edges to be bonded and
many different bonding techniques may be used. If bonding of the
edges is used, it may be advantages to bond the edge of the liner
in such a way so that the liquid impervious layer cover the edges
of the absorbent material.
From a processing standpoint, the most efficient and, therefore, a
preferred way to bond the layers of the laminate together is to
adhesively bond the layers to one another. The adhesives which can
be used will be readily apparent to those skilled in the art and
should be selected so that it will not lose its ability to hold the
layers together in the use environment. For example, the adhesive
holding the absorbent layer to the liquid impervious should not be
water-soluble or lose tack under refrigerated conditions. Further,
the adhesive should be selected should be a food grade adhesive,
since the products of the present invention may be used in an
environment which food will be present. Examples of such adhesives
include Findley L8260. When applying the adhesive to the layer of
the liner, care should be taken so that adhesive does not
completely coat an absorbent layer or the liquid pervious layer.
This may result in the liner not absorbing spilled liquids due to
the formation of a film an upper surface of the absorbent layer.
Methods are known to those skilled to prevent filming of an
adhesive, such as using a patterned roll to apply the adhesive or
lightly spraying the adhesive on a layer prior to attachment to
another layer.
Bonding the individual layers of the absorbent liner to create a
seal can be achieved by various means such as, for example, by
bonding using thermal or ultrasonic energy in combination with
pressure. However, it is important that the method of bonding does
not destroy the overall purpose of the individual layers. As each
of the layers includes thermoplastic polymers therein, bonding
along an edge 42 acts to create a seal that reduces and/or prevents
fluid from seeping out through the liner itself. The edge may be
bonded, for example, with a continuous seam or a series of closely
spaced point bonds. Desirably the bond or seal is positioned at the
edge up to about 1 cm from the outermost edge of the liner and vice
versa. In addition, it is also possible that the absorbent core not
extend completely to the liner edge 42 such that the seal comprises
a bond between the liquid impervious layer 16 and liquid pervious
layer 12. Further, it is also possible that the liquid impervious
layer wrap around the outside edge and over the liquid pervious
layer.
The liner of the present invention has additional advantages when
used in a refrigerator, in particular, the vegetable drawers. Since
the liner of the present invention is capable of absorbing
moisture, it also prolongs the life of fruits and vegetables
stored. This is because moisture on the surface of fruits and
vegetables tends to promote decay.
Fruits and vegetables continue to respire after they are harvested.
This respiration is the oxidative breakdown of the sugars,
starches, and organic acids to simpler molecules, including, but
not limited to water and carbon dioxide, with energy released in
the form of heat and metabolic energy. The rate of production of
oxygen and carbon dioxide during respiration can be affected by
altering certain of the characteristics of the atmosphere which
surrounds the fruit or vegetable. For example, temperature and
gaseous composition (e.g. oxygen, carbon dioxide, water and
ethylene concentrations) are known to affect the rate of production
of oxygen and carbon dioxide.
The major atmospheric variable affecting shelf life of fruits and
vegetables is the relative humidity. If the relative humidity is
too low transpirational damage occurs, which results in the loss of
turgidity, e.g. wilting, which leads to desiccation, increased
respiration, and ultimately, an unmarketable and inedible product.
If the relative humidity is too high, moisture can condense on the
fruit or vegetable. This leads to conditions favorable for
microbial growth due to the presence of free water, which
encourages the growth of bacteria and fungi, resulting in spoilage
of the fruit or vegetable. The present invention provides a
solution to the latter problem by absorbing liquid excess moisture
from the refrigerator while maintaining relative humidity. In
addition, any fruit or vegetable placed on the liner of the present
invention will be less likely to form moisture on the surface in
contact with the liner of the present invention, since the
absorbent nature of the liner will cause such moisture to be
absorbed into the liner.
In addition to placing a fruit or vegetable on the liner in a
refrigerator drawer or on a refrigerator shelf, the liner may also
be draped over the fruit or vegetable to help absorb moisture from
upper surfaces of the fruit or vegetable not in contact with the
liner. For example, a fruit or vegetable may be covered with
portions of the liner which are not in use. This will assist in
removing any condensation on the upper surfaces of the fruit or
vegetable.
Using the PUB bonding pattern on the liquid pervious layer has some
key advantages. The protrusions of the unbonded area elevates the
fruit or vegetable in contact with the liner. That is, the fruit or
vegetable is in contact with the protrusions of the PUB pattern and
the fruit or vegetable is generally held above the bonded area of
the PUB pattern. This allows for increased ventilation and/or vapor
transfer underneath a fruit or vegetable. In addition, these
protrusions provide an improved buffer between the absorbent layer
and the fruit or vegetable which results in insulating the surface
of the fruit or vegetable from the liquid moisture which has been
absorbed by the liner. Stated another way, the protrusions help
prevent the fruit or vegetable from coming into contact with the
moisture absorbed by the liner, which may result in the reduction
of the problems resulting from the contact of moisture with the
surface of the fruit or vegetable.
The liner of the present invention can further contain effective
amounts of scavengers for ethylene, carbon dioxide and oxygen
incorporated in to the odor controlling liquid absorbent layer to
assist in the control of these gases. Examples of these scavengers
are known to those skilled in the art or will be readily apparent
to those skilled in the art. Further, the liner of the present
invention can contain a preservative, such as an antibacterial
agent, a fungicide and other similar agents to prevent the growth
of bacteria and/or fungus on a fruit or vegetable placed on the
liner, or to prevent the growth of bacteria and/or fungus within
the liner. Preferable, but not required, the preservative is placed
in the absorbent layer. Suitable preservatives will be apparent to
those skilled in the art.
Further, the liner of the present invention is very effective in
absorbing meat juices that are often produced when meat is
defrosted on a refrigerator shelf. Uncooked meat sometimes contains
bacteria which is often destroyed during cooking. Many times, if
bacteria are present in the meat, these bacteria will also be
present in the meat juices. The liner of the present invention is
designed to be a disposable product; therefore, the liner which has
the absorbed meat juices can be thrown away after use, thereby
reducing the chances that bacteria will contaminate other
foods.
In addition to the above-disclosed uses of the liner of the present
invention, it is noted that the liner can be used in any location
which requires both liquid absorbency and odor control, for example
on food counters in kitchens, shoe boxes, closets, pet beds, cat
litter box liners and gym bags. Other possible uses will be
apparent to those skilled in the art.
EXAMPLES
Example 1
Using the process describe in U.S. patent application Ser. No.
09/419,039, filed on Oct. 15, 1999, on a wettable polypropylene
spunbond nonwoven fabric having a basis weight of 13.6 gsm (the
liquid pervious layer) a first coform layer is formed. The first
coform layer comprises 80% by weight pulp and 20% by weight
polypropylene. A second coform layer comprising 60% by weight pulp
and 40% by weight polypropylene and baking soda in an amount of 26
gsm is then formed on the first coform layer. The two layers of the
coform material have a combined basis weight of 176 gsm, including
the coform and backing soda. This three layer nonwoven web is then
adhesively attached to a polyethylene film having a thickness of 1
mil. using a food grade adhesive. The polyethylene film is attached
to the second coform layer which results in a four layer
structure.
Example 2
Using the process describe in U.S. patent application Ser. No.
09/419,039, filed on Oct. 15, 1999, on a wettable spunbond nonwoven
fabric prepared from a side-by-side bicomponent fiber, wherein one
component of the fiber is polyethylene and the other component is
polypropylene, having a basis weight of 42.4 gsm and a pattern
unbonded bond pattern (the liquid pervious layer), a first coform
layer is formed. The first coform layer comprises 80% by weight
pulp and 20% by weight polypropylene. A second coform layer
comprising 50% by weight pulp and 50% by weight polypropylene and
baking soda in an amount of 26 gsm is then formed on the first
coform layer. The two layers of the coform material have a combined
basis weight of 176 gsm, including the coform and backing soda.
This three layer nonwoven web is then adhesively attached to a
polyethylene film having a thickness of 1 mil. using a food grade
adhesive. The polyethylene film is attached to the second coform
layer which results in a four layer structure.
While the invention has been described in detail with respect to
specific embodiments thereof, and particularly by the examples
described herein, it will be apparent to those skilled in the art
that various alterations, modifications and other changes may be
made without departing from the spirit and scope of the present
invention. It is therefore intended that all such modifications,
alterations and other changes be encompassed by the claims.
* * * * *